1. Field of the Invention
The present invention relates to a ball screw device, and more particularly to a ball screw device having a lubricating device for effectively and easily lubricating the balls or the bearing members, and for facilitating the rotational movement of the ball nut and the screw shaft relative to each other in great rotational speeds.
2. Description of the Prior Art
Typical ball screw devices comprise a ball nut rotatably and/or moveably engaged onto a screw shaft, and normally arranged to allow the ball nut to be rotated and/or moved relative to the screw shaft in great rotational speeds. For allowing the ball nut to be smoothly rotated and moved relative to the screw shaft, a suitable bearing device or lubricating structure is further required to be provided and engaged between the ball nut and the screw shaft, for facilitating the rotational movement between the ball nut and the screw shaft.
For example, U.S. Pat. No. 5,809,838 to Miyaguchi et al. discloses one of the typical ball screw devices including an oil supplying structure having oil supplying holes formed in the ball nut and the outer ball race for supplying oil even when the typical ball screw device is in operation, and for eliminating the mounting and removal of the oil supplying pipes when supplying the oil. For lubricating the typical ball screw device, an annular gap will be formed between the ball nut and the outer ball race for filling and retaining the oil in the outer ball race.
However, the oil is simply filled into the annular gap of the outer ball race, but may not be forced into the endless ball train guiding passage of the ball nut that is provided for receiving the balls or bearing devices.
U.S. Pat. No. 6,364,058 to Nishide et al., and U.S. Pat. No. 6,732,600 to Greubel disclose two further typical ball screw devices including a ring chamber formed or arranged between an outer bearing part and an inner bearing part for receiving the lubricating oil.
However, similarly, the oil is simply filled into and retained in the ring chamber that is provided between the outer bearing part and the inner bearing part, but may not be forced into the moving path that is formed between a threaded spindle and a threaded nut and that is provided for receiving a roller bearing or balls.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages of the conventional ball screw devices for such as machine tools or the like.